Telephone system.



PATENTED AUG. 7, 1906.

B. R; GORWIN. TELEPHONE SYSTEM. APPLICATION FILED DEO.15, 1904- 2SHEETS-SHEET 1.

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BIO-827,787. PATENTED AUG. 7, 19.06. E. R. GORWIN. TELEPHONE SYSTEM.

APPLICATION FILED DBO. 15, 1904.

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"UNITED s'rArns ELMER R. CORWVIN,

PATENT orrron OF CHICAGO, ILLINOIS, ASSIGNOR TO MONARCH TELEPHONEMANUFACTURING COMPANY, OF CHICAGO. ILLINOIS, A CORPORATION OF ILLINOIS.

TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Aug. 7, 1906.

Application filed December 15,1904. Serial No. 236,958.

1'0 alt 1071,0711, it may concern.-

Be it known that I, ELMER R. CoRwIN, a citizen of the United States ofAmerica, and a resident of Chicago, county of Cook, and

State of Illinois, have invented a new and useful Improvement inTelephone Systems, of which the following is a specification.

My invention relates to that class of telephone systems in which signalsare set before the operators at a manual switchboard b the removal ofthe receiver of the subscri ers telephone from its hook, energy beingthus supplied to the line for all purposes of signaling and speechtransmission from a source in the central o'l'lice, and in which theline, if desired, may be terminated in a plurality of line-jacks in amultiple switchboard at the central oflice.

In many standard systems in use at the present time of the general typewhich I have just indicated the cord and plug circuits of theswitchboard are of three conductors. In my system I limit theseconductors to two. In many systems involving supervisory lampsignalsassociated with the plugs of the cordcircuit either a strand in the cordis utilized to energize the lamp upon the plug being placed in use and arelay is associated with the cord-circuit and the lamp-circuit to openthe latter upon the answer of the called subscriber, or two sets ofrelays are employed, two for each lamp, one serving to place the lamp inaction upon the connection of a plug with the line and the other toextinguish it upon the answer of the called subscriber. In my system butone relay per supervisorylamp is required, this receiving its energy inseries with the line associated with it, and yet in such a manner as notto interfere by the inductance which it containswith the propertransmission of speech over the line, as is true in other systems inwhich a series-relay is'involved as a function of the cord-circuit.

l /Iy invention is illustrated in the accompanying drawings, in which-Figure 1 illustrates a pair of lines and a cord-circuit adapted toconnect them. Fig.

2 illustrates an alternative form of cord-circuit for use with suchlines; and Fig. 3 illustrates in a schematic manner the connection oftwo stations through their lines and the cord-circuit shown in Fig. 1.

Similar characters refer to similar parts throughout the several views.

Referring now to Fig. 1, 1 is a station on a calling-line formed of thelimbs 2 and 3. 4 is a station on a called line formed of the limbs 5 and6'. Upon the removal of the receiver at station 1 from its hook, currentwill flow from the battery B, through the line-relay 7, over the limb 2,through station 1 to the central office on limb 3, through thecontact-piece 8 to the armature 9 of the relay 7, through thecontact-piece 10 to the armature 11 of the relay 12 to ground. The relay7 will thus be energized and by a construction which adapts the armature9 to make contact with the piece 13 before breaking from the piece 8 acircuit will be closed through the line-lamp 14 before the ground isremoved from the limb 3 at the point 8. Current will then flow from thebattery B, through the relay 7, the lamp 14 via 13, 9, 10, and 11 toground. This illuminating the lamp 14 will be a signal to the operatorthat a call requires to be answered, as the lamp 14 is adapted to bebrought to a proper signaling brilliancy by the voltage of the batteryB, while in series with the Winding of the re lay 7. The operator inanswering by inserting the plug composed of the elements 15 and 16 intoa jack, as 17, of the calling-line will energize the relay 12 by currentfrom the battery B over the conductor 18 via the armature 19 and thecontact 20 of the relay 21, through the lamp 22, the sleeve 16 of theplug, the sleeve 23 of the jack 17 or another quite like it, similarlyconnected to and through the winding of the relay 12 to ground. Byattraction of its armature 11 this relay will break contact between itand the point 10, which will extinguish the linelamp 14. It will beobserved that unless a plug is in a spring-jack of the callingline, as17 the attraction of the armature 9 has left no path for the current toflow over the line after the setting of the line-signal until theanswering of the call by the operator, when this current may again fiowthrough the line, being, as before, from the battery B, through therelay 7 over the limb 2, through the telephone and to the oflice on .thelimb 3, but now passing from this limb by contact of the spring 24 ofthe jack 17 to the tip 15 of the answering-plug, through the relay 21,

thence by the sleeve 16 of the plug and the bushing 23 of the jack 17 toground through the relay 12. It will be seen that this se ries ofelements includes all three relays 7, 12, and 21. These are all of suchnature as to be energized by series current through the line,

the telephone, and themselves and will beaffected as has beenparticularly described above. :Contact between elements 19 and 20 of therelay 21 will be broken, extinguishing the lamp 22, signifying that thecalling subscriber is at his telephone. In addition such a portion ofthetotal voltage of the battery will exist and the difierence ofpotential between the bushing 23 (and others connected to it) andthefearth as is controlled by the drop of potential through the relay12. This will providecondition s for a busy test later to be described.Upon learning the number of the called subscriber the operator willinsert the other plug ofthe cord-circuit (designated asawhole 25) in anaccessible jack of the called line, will ring by means of the rin ingkey26, and upon the answering of the b subscriber, this being shown by theextinguishrnent of the lamp '27, will abandon connection forconversation until such time as the relighting of the lamps 22 and 27shall indicate the fact that both parties to the conversation have hungup their receivers, whereupon she will disconnect the 'plugs from thejacks. Preliminary, however, to inserting the plug 25 into the jack, as

' 28 of the called line, formed of limbs 5 and 6,

ftheoperator will rnake the usual busy test ,bytouching the tlp of theplug 25 to the ex- ,posed bushing of the jack desired to be taken.

If that jack is one of a line elsewhere con- 'nected with a potentialabove that of the earth, it;willbe found busy, and a click willbe,observed inher telephone. This will be because the ground connectionwith the operators telephone-receiver 29 enables her to 'percelve thepresence of such test-potentials, the circuit when such a click isheardbeing as follows; Ifthe subscriber whose line is being tested has hisreceiver from the hook, current will beflowin'g through the relay 30,connected. to ground from the test-bushings of the 1 test bushing w1llcause current to flow from line, The potential existing at the touched jthetip 31 of the plug 25 through the ringingkey in the manner usual insuch circuits, and, as the listening-key 32 is operated at that Vthrough his receiver, but will exist'by current from, the,battery B overthe conductor 18, through the contact of the piece 36 with the armature37 of the relay 38, thence via the ground at the relay 30.

called lamp 27, through conductor 42 and the ringing-key to the sleeve39, thence to the various testbushings of the called line, and to In thedescription of this path, beginning with the conductor 18, it is to beunderstood that the various numerals indicate homologous parts in adistant cord-circuit which is causing the called line to be busy. Itwill be seen that under the two sets of conditions which may cause thecalled line to busy test the same result is achieved, and whenever oneof them does not exist'the other will, and no unguarded interval willexist at any time. During the operated condition of the listening-key 32not only will the test conditions described between the tip 31 and theplug 25 and the ground connection of her receiver exist, but theoperators telephone-circuit as a whole will be bridged in series withthe condenser 40 across the conductors 41 and 42 of the cord-circuit. Itwill be observed that the release of the listening-key 32 connects thelimbs 41 and 42 of the cord-circuit directly through to the terminals ofthe plug 25 for unimpeded conversation, although during the operation ofthe -key such conversation could have taken place through the additionalpath, including the condenser 40, one of which only exists per operatorsset. The ringing-key 26, which is ofv the usual type, adapted to connectthe terminals of the ringing generator G'to the conductors '31 and 39 ofthe plug 25, also isconnected, through im pedancecoil 43, with the livepole of the battery 'B. When such connection is made by the operation ofthe ringing-key 26, current will flow from'the battery B through thecoil 43 via the sleeve 39 of theplug 25, over the conductor from thejack-bushing to and through the relay'30 to ground. This, by

breaking the contact between the armature 44 and its point 45, willisolate the limb 5 of the line from any connection with the battery orthe ground and will thus permit ringingcurrent to pass over the linethrough the condenser 46 and the" ringer 47 at the called station, againto the central ofliceov'er the limb 6, through'thecondenser 48, again tothe ringing-generator 'at its opposite conductor.

There will thus be no tendency to set a false signalbefore the distantoperator by an act of ringing on the part of any operator upon any line,as whatever motions might be caused on the part of the armature of there lay 49, due to accidental conditions of potential, the circuit ofthe-lamp 50 is open at the contact 45.

Referring now to Fig. 3 and comparing therein the reference characterswhich it contairis withsimilar reference characters in Fig. 1, a clearidea may be gained of the circuit rela- ,tions' which exist during thetime of conversation. Inasmuch as it'is the'oflice of the relays 21 and38 to respond to a flow of direct current for the control of thesupervisory signals, they must be of such dimensions electrically andmechanically as will enable them to indicate with decisiveness Whetheror not the receivers of the calling and called subscribers are on or offtheir hooks. This, however, is a function of direct current flowingthrough the relays in question. The alternating or otherwise fluctuatingcurrents pro duced by speech at the substations need not flow throughthese relays, and the best conditions of transmission aresecured whenthey do not. A suflicient impedance in the relays 21 and 38 for a verylarge prevention of short-circuiting voice-currents may be accomplished,together with a-low resistance to direct currents, by a suflicientlygenerous design involving the use of enough iron and copper. Thecondensers 52 and 53, being relatively transparent to voice-currents,permit conversation between the connected stations.

Fig. 2 illustrates an alternative arrangement of apparatus in acord-circuit adapted to be used with the line-circuits shown in Fig. 1.All that has been described with reference to the listening-key 32 andits relation to the operators telephone-circuit, the ringing-key 26 andits relation to the giving of a signal to the called subscriber applyequally to the arrangement here shown. The condensers 52 and 53 and therelays 21 and 38 are omitted, however, from this circuit, their officesbeing served by the re eatingcoils 54 and 55. The repeating-coil 54 hastwo windings, one of them composed of the conductor (indicated as 56 and57) outside of the coil, being connected to the terminals 15 and 16 ofthe answering-plug. The other winding of the repeatingcoil 54 (indicatedas 58 and 59) is connected directly in series with one of the windingsof the coil 55. The second winding of the latter coil makes eXit as theconductors 60 and 61. The winding connecting the conductors 56 and 57 inthe coil 54 establishes such a bridge upon the callingsubscribers lineas is established in Figs. 1 and 3 by the relay 21, and the windingconnected to the conductors 60 and 61 stands in a similar relation tothe line of the called subscriber. As there is no other path, such asthat through the condensers 52 and 53 in the other figures, all currentcirculating in the calling-line must pass through the winding of therepeating-coil 54. In so far as these currents are direct they willenergize the core of the repeating-coil, attracting the armature 62, andopening at the point 63 the circuit of the lamp 64, so that during allthe time of conversation no path will be provided from the battery Bthrough the lamp 64 to the sleeve 16 of the answering-plug, and thusover the path previously described to permit the illumination of thesignal. The clo sure of the armature 62 upon the point 63 at thetermination of the conversation will perconstituting a series portion ofthe called line.

The mechanical construction of the relayarmature 9 shall be such that itresponds promptly to controlling changes of energy in its core 7, whilethe mechanical construction of relay-armature 11 shall be such that itresponds sluggishly to controlling changes in its core 12. Armature 9thus becomes a quick armatureand armature 11 a slow armature. Thenecessity for this arrangement of armature speeds arises from thecondition of circuits permitting the relighting of the signal-lamp 14after the withdrawal of the connecting-plug if contact 10 11 shouldclose before contact 9 13 has opened. With this arrangement of armaturespeeds the sequence of events following the disconnection of the plugfrom the jack is as follows: Quick armature 9 makes contact 8 9, thenbreaks contact 9 13. Then slow armature 11 makes contact 10 11, and allparts remain in their normal position.

While I have herein shown and particularly described specificconnections for the condensers inthe line-circuits and particular formsof signaling circuits and devices, I do not wish to be limited in allembodiments of the invention to the precise apparatus specificallyillustrated.

It is obvious that various changes may readily be made in the system ofthe invention herein shown without departing from the spirit of myinvention.

Having thus described my invention, what I claim is 1. In a telephonesystem, the combination with two telephone-substations and theirconnecting-lines, of relays and condensers so arranged as to give aconversation condition in which the line-relay, cut-oil relay andsupervisory-relay in series with each other and with the line andsubstation equipment furnish path for current-supply for that line towhich the relays pertain, and in which path for the fluctuatingspeech-currents passing from line to line is furnished throughcondensers but not through any winding of any relay, substantially asdescribed.

2. In a telephone system, the combination with two telephone-substations and their connecting-lines, of relays and condensers soarranged as to give a conversation condition in which the line relay,cut-off relay and supervisory relay, in series with each other and withthe line and substation equipment 1 with each other,substantially asdescribed.

cut-oil relay adapted to e'l'lace the visual sigfurnish path forcurrent-supply for that line to which the relays pertain, the line andcutoil relays being permanently parts of the equipment of the line, andthe supervisory equipment being a part of the equipment of thecord-circuit used to connect the lines, and in which path thefluctuating speechcurrents passing from line to line is furnishedthrough condensers but not through any winding of any relay,substantially as described.

3. In a telephone system, the combination of a telephone-line, aline-relay adapted to give a visual signal when the circuit of said lineis closed at the substation and as long as no plug is inserted in anyjack of the line, a

nal when a plug is inserted in a ack of the line, the windings of thetwo relays being permanently connected to one of the conductors of theline, a condenser inserted in the conductor of the line between thepoint of connection of the line-relay and the point of connection of thecut-off relay, and a ground upon the remaining conductor of the linethrough a contact of the cut-oil relay, substantially as described.

4; In a telephone system, the combination of a telephone-line havingline and cut-ofl relays, with a cord-circuit plug having a supervisoryrelay, giving a circuit for the supply of current to the line, throughthe line-relay, cut-oil and supervisory relays, the two members of theline and the telephone-substation, all of the parts named being inseries with each other, substantially as described.

5. In a telephone system, the combination of two telephone-lines eachhaving line and cut-off relays, with a cord-circuit having twosupervisory relays, forming circuits, when connected, for supply ofcurrent to each line from a common current source through the line andcut-off relays of that line, the supervisory relay pertaining to thatlines plug, the two members of that line and the substation-telephone ofthat line, all in series 6. In a telephone system, the combination of.two telephone-lines each having line and cut-ofl' relays, with acord-circuit havingtwo supervisory relays, forming a circuit, whenconnected, for supply of current to each line from a common currentsource through the line and cut-off relays of that line, the supervisoryrelay pertaining to that lines plug, the two members of that line andthe substation of that line, all in series with each other, and forminga circuit, when connected, for the passage of fluctuatingspeech-currents from line to line through condensers but not through thewinding of any relay, substantially as described.

7. In a telephone system, the combination of a telephone-line withmultiple jacks,- a

to ground through the winding of a cut-ofi" relay permanently connectedbetween the test-rings and ground; and a second busytest circuitextending from ground through a battery, a winding of a relay 49, thelimbs of the-line and the substation-telephone, the

jack, the tip of the plug, the two talking-conductors of the connectedcord and a bridged supervisory relay, and the sleeve of the plug, to thetest-ring of the jack, and extending thence as in said first busy-testcircuit to ground through the winding of a cut-off relay permanentlyconnected between the test-rings and ground; said two busy-test circuitsbeing alternative, the first being complete when the circuit between thelinelimbs at the substation-telephone is open and the second beingcomplete when the circuit between the line-limbs at thesubstationtelephone is closed, substantially as described.

8. In a telephone system having telephone-lines with multiple jacks, thecombination of a busy-test circuit a portion of which at all times isformed by the circuit from the test-ring of the multiple jacks of a linethrough the cut-0H relay to ground, said busy-test circuit beingcompleted prior to the answering of the called subscriber throughcircuits local to the telephone central office, and after the answeringof the called subscriber through circuits involving telephone-substationapparatus, substantially as described.

9. In a telephone system having telephone-lines with multiple jacks, thecombination of a busy-test circuit a portion of which at all times isformed by the circuit from the testrings of the multiple jacks of a linethrough the cut-ofl' relay to ground, said busy-test circuit beingcompleted rior to the answering of the called subscri er by a circuitentirely local to the central o'l-Iice and including one of theconductors of the connecting cordcircuit, with means by which upon theanswering ofthe called subscriber the busy-test circuit is changedautomatically to be completed throughthe two conductors of theconnecting cord-circuit, the supervisory relay, the two limbs of theline, the substationtelephone and the line-relay, substantially asdescribed.

10. In a telephone system having telephone-lines with multiple jacks,the combination of a busy-test circuit a portion of which at all timesis formed by the circuit from the test-rings of the multiple jacks of aline through the cut-off relay, said busy-test circuit being completedprior to the answering of the called subscriber by a circuit entirelylocal to the central ol'lice and including one of the conductors of theconnecting cordcircuit, with means by which upon the answering of thecalled subscriber the busytest circuit is changed automatically to becompleted through the two conductors of the connecting cord-circuit, thesupervisory relay, the two limbs of the line, the substation-telephone,and the line-relay, substantially as described.

11. In a telephone system with multiple jacks, the combination of abusy-test circuit existing prior to the answering of the calledsubscriber, said circuit comprising one of the conductors of theconnecting cord pair, the cut-off relay and other connecting parts, withmeans operative upon the answering of the called subscriber by whichsaid busy-test circuit is destroyed and a current-supply circuitestablished for the substation-telephone through the line-relay, the twolimbs of the line and the substation-telephone, the two conductors ofthe connecting-plug and its supervisory relay and the cut-oii relay ofthe line, said current-supply circuit forming also a busy-test circuitfor said lines multiple jacks, substantially as described.

12. In a telephone system having telephone-lines with multiple acks, thecombination of a telephone-line and substationtelephone, the multiplejacks of said telephone-line,a line-relay, a cut-0H relay, a plugadapted to connect with any one of said multiple jacks, circuitsassociated with said plug, and a busy-test circuit existing when saidplug is inserted into any one of said multiple jacks, said busy-testcircuit being at all-times partly in a circuit from said multiple jacksthrough said cut-off relay, and adapted to be completed either throughsaid circuits associated with said plug, or through said line-relay,telephone-line and substationtelephone and the said circuits associatedwith the said plug, alternatively, substantially as described.

13. In a telephone system having telephone-lines with multiple jacks,the combination of a telephone-line and substationtelephone, themultiple jacks of said telephone-line, a line-relay, a cut-off relay, a

plug adapted to connect with any one of said multiple jacks, circuitsassociated with said. plug, a busy-test circuit existing when said plugis inserted into any one of said multiple jacks, said busy-test circuitbeing at all times formed. partly of a circuit from said multiple jacksthrough said cut-off relay, and adapted to be completed when thesubstation telephone-circuit is open through said circuits associatedwith said plug, and means adapted to change said busy-test circuitautomatically when the substation-telephone circuit is closed to becompleted through the line-relay, the telephone-line and substation-telehone, and the circuits associated with sai plug, substantiallyv asdescribed.

14. In a telephone system having telephone-lines with multiple jacks,the combination of a telephone-line and substationtelephone, multiplejacks. connected with said telephone-line, testrings forming parts ofsaid multiple jacks, a cut-off relay, circuits from the said test-ringsto and through the said cut-ofl relay, a line-relay, a plug adapted toconnect with any one of said multiple jacks, a plug-circuit of twoconductors connected to said plug, a bridged supervisory relay and asignal device, and a busy-test circuit when said plug is inserted intoany one of said multiple jacks, a portion of said busytest circuit beingat all times formed by the circuit from the test-rings of said multipleiacks to and through the cut-off relay, said busy-test circuit beingadapted to be completed when the substation-telephone circuit is openthrough the signal device and one of the said two conductors of saidplug-circuit, and adapted to be completed when the sub station-telephonecircuit is closed through the line-relay, the telephone-line andsubstation-telephone and the circuits associated with said plug,substantially as described.

15. In a telephone. system, the combina tion of a telephone-line andsubstatiomtelephone, multiple jacks connected with said telephone-line,a plug adapted to connect with any one of said jacks, circuitsassociated with said plug comprising two conductors and a bridgedsupervisory relay, a line-relay adapted to give a visual signal when thesubstation-telephone circuit is closed, a cut-off relay adapted toefface the line-signal when the plug is inserted into any jack of thetelephone-line, and a source of current, the line and cut-off relaysbeing permanently connected to the telephone-line and adapted to connectsaid line permanently to said source of current and adapted when saidplug is inserted into any one of said jacks to complete a circuit forcurrent from said source through said telephone-line andsubstation-telephone and said circuits associated with said plug,comprising two conductors and a bridged supervisory relay, substantiallyas described.

16. In a telephone system, the combination of the battery B, relay 49,the two limbs of a telephone-line, the substation telephone,

relay 38 and relay 30, all being connected in having three relays, onerelay as 21 or 38 of each line being of high impedance and the tworemaining relays of each line being connected in series with each other,with the high-impedance relay and with the line, with two condensers 52and 53 connecting the two lines at the terminals of the high-impedancerelays, and with a condenser as 48 or 65 for each line connected aboutthe two remaining relays of each line, adapted to form aspeechtransmission circuit between the two substation-telephones throughthe four condensers but not throu h the winding of any relay,substantially as escribed.

.18. In a telephone system, the combination of two substation-telephonesand two telephone lines connected. therewith, each having'a sourceof'current and three relays,

Inanently to the two limbs of said line, mu1ti ple jacks connected withsaid telephone-line, test-rings connected with said multiple jack's,'aplug adapted to connect with said multiple onerelay as 21 or 38 of eachline beingof high impedance and the two remaining relays of each linebeing connected in series with each other, with the high-impedance relayand with the line, with two condensers 52 and 53 connecting the twolines at the terminals of the high-impedance relays, and with acondenseras 48 or for each line connected about. the two remainingrelays and the source of current of each line, 'adapted to form aspeech-transmission circuit between the two substation-telephonesthrough the four condensers but not through the winding of any relay,substantially as described.

19,. The combination in a telephone sys tem, of a telephone-line of twolimbs, a substation-telephone, two relays connected perjacks, conductorsassociated with said plug, a signal 5 device connected with said plug, asource of electric potential, a test-circuit when thesubstation-telephone circ uit'is open and said plug is connected withone of said multiple jacks adapted to give testcurrent from said batterythrough said signal device and conductors of s aid plug to thetest-rings of the, m ultiple jacks, a test-circuit when thesubstation-telephoneis closed, and said plug is connected with one ofsaid multiple acks, adapted to give test-current from said batterythrough one of saidrelays, the two limbs of said linefthesubstation-telephone and the conductors associated'with said plug to thetest-rings ofthe jacks, and means adapted to change the test conditionfrom the one testcircult to the other as the substation-tele phonecircuit may beopened or closed,'sub

stantially as described. I

.20. The combination in a telephone sys 'tem of a telephone-line of twolimbs, a sub station-telephone, two relays connected p'ermanently to thetwo limbsof saidline, multiple jacks connected with said telephone-line,test-rings connected with'said multiple jacks,

a plug adapted to connect with said'multiple jacks, conductorsassociated with plug, a source of electric potential, a test-circuitwhen the substation telephone circuit is open and said plug is connectedwith one of said multiple jacks adapted to give test-current from saidbattery through conductors of said plug to the test-rings of themultiple jacks, a testeircuit when the substation telephone is closedand said plug is connected with one of saidmultiple acks adapted to givetest-current from said battery throughone of said relays, the two limbsof saidline, the substation-telephone and the conductors associated withsaid'plu'g to the test-rings of the jacks, and means adapted to changethe test condi tion from one test-circuit to the other as thesubstation-telephone circuit may be opened or closed, 'substantially asdescribed.

21. A telephone-exchange system including a plurality of telephone-linesextending from substations to an exchange, connecting means'at theexchange for uniting lines in conversationflineand supervisory ordisconnect signal circuits, and condensers in talking sides of saidtelephonedinesserving to separate said signaling circuits.

22. A telephone-exchange system including a' plurality oftelephone-lines extending from substations to an exchange, connectingmeans at the exchange for uniting lines'for conversation, line-signaland cut-ofl relay circuits, and condensers in talking sides of saidtelephone-lines serving to separate said line-signal and cutoffrelay-circuits.

23. A telephone-exchange system including a plurality of telephone-linesextending from substations to an exchange, connecting means at theexchange for uniting lines in conversation, line and supervisory ordisconnect signal circuits, condensers in talking sides of saidtelephone-lines serving to separate said signaling-circuits, and cut-offrelays for the telephonelines each adapted for inclusion, bysaidconn'ecting'means, in a supervisory or disconnect signal circuit.

24. A telephone-exchange system including a plurality of telephone-linesextending from substations to an exchange, connecting cuits includingrelays, and condensers in talking sides of said telephone-lines servingto separate s aidline-signal and cut-off relay circuits. I u i 26. Atelephone-exchange system includ- III) ing a plurality of telephonedinesextending I from substations to an exchange, connecting means at theexchange for uniting lines in conversation, line and supervisory ordisconnect signal circuits, said line-signal circuits includingline-relays, and condensers in talking sides of said telephone-linesserving to separate said signaling-circuits. 1

27. A telephone-exchange system including a plurality of telephone-linesextending from substations to an exchange, connecting means at theexchange for uniting lines for conversation, line-signal andcutbfi relaycircuits, said line-signal circuits including linerelays, and condensersin talking sides of said telephone-lines serving to separate saidlinesignal and cut-oft relay circuits.

28. A telephone-exchange system including a plurality of telephone-linesextending from substations to an exchange, connecting means at theexchange for uniting lines in conversation, line and supervisory ordisconnect signal circuits, said line-signal circuits includingline-relays, condensers in talking sides of said telephone-lines servingto separate said signaling-circuits, and cut-off relays for thetelephone-lines each adapted for inclusion, by said connecting means, ina supervisory or disconnect signal circuit.

29. A telephone-exchange system includ ing a plurality oftelephone-lines extending from substations to an exchange, connectingmeans at the exchange for uniting lines in conversation, line andsupervisory or disconnect signal circuits each including a relay, andcondensers in talking sides of said telephone-lines serving to separatesaid signalingcircuits.

30. A telephone-exchange system including a plurality of telephone-linesextending from substations to an exchange, connecting means at theexchange for uniting lines in conversation, line and supervisory ordisconnect signal circuits each including a relay, condensers in talkingsides of said telephonelines serving to separate saidsignaling-circuits, and cut-ofi relays for the telephonelines eachadapted for inclusion, by said connecting means, in a supervisory ordisconnect signal circuit.

31. A telephone-exchange system including a plurality o'ftelephone-lineS extending from substations to an exchange, connectingmeans at the exchange for uniting lines in conversation, a line-signalcircuit and an additional signal-controlling circuit for eachtelephone-line and connected with the same talking side of thetelephone-line, and a con denser in said talking side of eachtelephoneline located between the connections of the correspondingcircuits with the corresponding talking side of the correspondingtelephone-line.

32. A telephone-exchange system including a plurality oftelephone-linesextending from substations to an exchange, connecting means at theexchange ior uniting lines in conversation, a line-signal circuit and anadditional signal-controlling circuit including a cut-oii relay for eachtelephone-line and connected with the same talking side of thetelephone-line, and a condenser in said talking side of eachtelephone-line located between the connections of the correspondingcircuits with the corresponding talking side of the correspondingtelephone-line.

33, A telephone-exchange system including a plurality of telephone-linesextending from substations to an exchange, connecting means at theexchange for uniting lines in conversation, a line-signal circuitincluding a relay and an additional signal-controlling circuit for eachtelephone-line and connected with the same talking side of thetelephoneline, and a condenser in said talking side ofeachtelephone-line located between the connections of the correspondingcircuits with the corresponding talking side of the correspondingtelephone-line.

34. A telephone-exchange system including a plurality of telephone-linesextending from substations to an exchange, connecting means at theexchange for uniting lines in conversation, a line-signal circuitincluding a relay and an additional signal-controlling circuit includinga cut-oii' relay for each tele phone-line and connected with the sametalking side of the telephone-line, and a condenser in said talking sideof each telephoneline located between the connections of thecorresponding circuits with the corresponding talking side of thecorresponding telephone-line.

35. A telephone-exchange system including a plurality of telephone-linesextending from substations to an exchange, connecting means at theexchange for uniting lines in conversation, line and supervisory ordisconnect signal circuits, and condensers in talking sides of saidtelephone-lines serving to separate said signaling-circuits, saidcircuits corresponding to each telephone-line includ-- ing a source ofcurrent common thereto.

36. A telephone-exchange system incluling a plurality of telephone-linesextending from substations to an exchange, connecting means at theexchange for uniting lines for conversation, line-signal and cut-offrelay circuits, and condensers in talking sides of said telephone-linesserving to separate said line-signal and cut-oil relay circuits, saidcircuits corresponding to each telephone-line including a source ofcurrent common thereto.

37. A telephone-exchange system. including a plurality oftelephone-lines extending from substations to an exchange, connectingmeans at the exchange for uniting lines in conversation, line and.supervisory or disconnect signal circuits, condensers in talking sidesof said telephonelines serving to sepa- IIC IIS

I rate said signaling-circuits, and cut-oil relays for thetelephone-lines each adapted for inclusion, by said connecting means, ina supervisory or disconnect signal circuit, said circuitscorrespondingto each telephone-line including a source of current common thereto.

38. A telephone-exchange system including a plurality of telephone-linesextending from substations to an exchange, connecting means at theexchange for uniting lines in conversation, line and supervisory ordisconnect signal circuits including relays, and con densers in talkingsides of said telephonelines serving to separate saidsignaling-circuits, said circuits corresponding to each telephone-lineincluding a source of current common thereto.

39. A telephone-exchange system including a plurality of telephone-linesextending from substations to an exchange, connecting means at theexchange for uniting lines in conversation, line-signal and cut-o'fi"relay circuits including relays, and condensers in talking sides of saidtelephone-lines serving to separate said line-signal and cut-oil relaycircuits, said circuits corresponding to each telephone-line including asource of current common thereto.

40. A telephone-exchange system including a plurality of telephone-linesextending from substations to an exchange, connecting means at theexchange for uniting lines in conversation, line and supervisory ordisconnect signal circuits, said line-signal circuits including linerelays, and condensers in talk ing sides of said telephone-lines servingto separate said signaling-circuits, said circuits corresponding to eachtelephone-line including a source of current common thereto.

41. A telephone-exchange system including a plurality of telephone-linesextending from substations to an exchange, connecting means at theexchange for uniting lines for conversation, line-signal and cut-ofirelay circuits, said line-signal circuits including line-relays, andcondensers in talking sides of said telephone-lines serving to separatesaid line-signal and cut-oil relay circuits, said circuits correspondingto each telephone-line .in cluding a source of current common thereto.

42. A telephone-exchange system including a plurality of telephone-linesextending from substations to an exchange, connecting means at theexchange for uniting lines in conversation, line and supervisory ordisconnect signal circuits, said line-signal circuits includingline-relays, condensers in talking sides of said telephone-lines servingto separate said signaling-circuits, and cut-off relays for thetelephone-lines each adapted for inclusion, by said connecting means, ina supervisory or disconnect signal circuit, said circuits correspondingto each telephone-line including a source of current common thereto.

43. A telephone-exchange system includ ing a plurality of telephonedinesextending from substations to an exchange, connecting means at theexchange for uniting lines-in conversation, line and. supervisory ordisconnect signal circuits each including a relay, and condensersintalking sides of saidtelephone-lines serving to separate saidsignalingcircuits, said circuits corresponding to each telephone-lineincluding a source of current common thereto.

44. A telephoneexchange system includinga plurality of telephone-linesextending from substations to an exchange, connecting means at theexchange for uniting linesin conversation, line and supervisory ordisconnect signal circuits each including a relay, condensers in talkingsides of said telephonelines serving to separate saidsignaling-circuits, and cut-oil relays for the telephonelines eachadapted for inclusion, bysaid connccting means, in a supervisory ordisconnect signal circuit, said circuits corresponding to eachtelephone-line including a source of current common thereto.

45. A telephone-exchange system including a plurality of telephone-linesextending from substations to an exchange, connecting means at theexchange for uniting lines in conversation, a line-signal circuit and anadditional signal-controlling circuit for each telephone-line andconnected with the same talking side of the telephone-line, and a condenser in said. talking side of each telephoneline located between theconnections of the corresponding circuits with the corresponding talkingside of the corresponding telephoneline, said circuits corresponding toeach telephone-line including a source of current common thereto.

46. A telephone-exchange system includ ing a plurality oftelephone-lines extending from substations to an exchange, connectingmeans at the exchange for uniting lines in conversation, a line-signalcircuit and an additional signal-controlling circuit including a cut-oilrelay for each telephoneline and connected with the same talking side ofthe telephone-line, and a condenser in said talking side of eachtelephone-line located between the connections of the correspondingcircuits with the corresponding talking side of the correspondingtelephone-line, said circuits corresponding to each telephone-lineincluding a source of current common thereto.

47. A telephone-exchange system including a plurality of telephone-linesextending from substations to an exchange, connecting means at theexchange for uniting lines in conversation, a line-signal circuitincluding a relay and an additional signal-controlling circuit for eachtelephone-line and connected with the same talking side of thetelephoneline, and a condenser in said talking side of eachtelephone-line located between the connections of the correspondingcircuits with the corresponding talking side of the correspondingtelephone-line, said circuits corresponding to each telephone-lineincluding a source of current common thereto.

48. A telephone-exchange system including a plurality of telephone-linesextending from substations to an exchange, connecting means at theexchange for uniting lines in conversation, a line-signal circuitincluding a relay and an additional signal-controlling circuit includinga cut-off relay for each telephone-line and connected With the sametalking side of the telephone-line, and a condenser in said talking sideof each telephoneline located between the connections of thecorresponding circuits With the correspond ing talking side of thecorresponding telephone-line, said circuits corresponding to eachtelephone-line including a source of current common thereto.

49. In a telephone-exchange system, the combination With telephone-linesextending from substations to an exchange, means for from substations toan exchange, means for connecting telephone-lines in conversation,signalcircuits corresponding to each telephone-line, and a condenser inone side of each of said telephone-lines serving to separate thecorresponding signaling-circuits, said signaling-circuits including acommon source of current. a D

Signed by me at Chicago, county of Cook, State of Illinois, in thepresence of tWo Witnesses.

ELMER R. OORWIN.

Witnesses:

EVA A. GARLOOK, DAVID S. HULFISH

